Glass render problem
To improve:


Add thickness to the glass. Otherwise, it will be considered as a big block of glass, which certainly makes it unrealistic. You can add a Solidify modifier to it, with a very small thickness value:





Add a "skybox" to hold all objects in. It can be told from the reference image that there seems to be an indoor lighting setup, so you may want to build a simple "photostudio" for that, instead of an open boundless world:






Here is one solution for the lighting setup:


Set a background plane with material nodetree like this:





Create a box with the same material on each face:





In the box, add a few area lamps:





Tweak everything until satisfied.


A test render with comparison:







EDIT:

After reanalyzing the reference case, since it seems a bit "fake", it is very likely that the bulb material can be simulated without refraction property, which means, no glass shader needed, and no Solidify modifier needed.

So it could be a mixture of Glossy and Transparent:



Test render with comparison:





NOTE: Since no calculation for refraction, it is much quicker to render. Time can be dramatically saved in this way.